Logical science always creates what is known as "limited number of possible options". the most simple form is A or not A, where one thing either exists or doesnt. the more complicated is more than one thing, such as: "A and B", "not A and not B", "A and not B", or "not A and B".
text writing follows patterns which are usually divided on these categories:
- Repetition and no repetition
- talking about same topic and not talking about same topic
- Same size of text and variety of sizes
In other words, 3 categories concern repetition, topic and size.
take example of famous speech rewritten to make it shorter:
"We shall fight on the beaches, we shall fight in the skies, we shall never surrender."
this text repeats "We shall fight" 2 times, and repeats "We shall" 3 times. this repetition is what gave text its charm, starting each sentence with same "We shall".
However, repetition isnt always good. But "not repetition" is variety, in other words, "not repetition" is something which is unique.
Such as sentence which has no any repeating words, and sentence which uses words not repeated anywhere else in text.
However, it is universally accepted truth that repetition and not repetition both arent enough on their own. You can write a text where no word repeats, and it will be a bit boring text. You can write a text where each word repeats at least twice in text, and it will be too much repetition.
It is universally agreed that combining these elements, variety and repetition, produces better text. Same with size and topic. You want to have some sentences be of same length, and some others vary. You want to have some sentences talking of same topic, and some others talking about something different.